Acoustic coordinated reset (CR) neuromodulation therapy is a form of noninvasive neuromodulation therapy for treating primary tinnitus, in particular, the frequency-specific, often tonal tinnitus commonly seen in these patients. See, for example, “Counteracting tinnitus by acoustic coordinated reset neuromodulation,” Restor. Neurol. Neurosci. 30(2):137-159. Tass et al., 2012.
Acoustic CR neuromodulation uses acoustic signals that stimulate the auditory neural tracts as they account for hearing level and psychoacoustic characteristics of the tinnitus percept (Tass et al., 2012). These techniques employ well-accepted neuroplasticity principles and were developed using computational modeling. See, for example, “A model of desynchronizing deep brain stimulation with a demand-controlled coordinated reset of neural subpopulations,” Biol Cybern 89(2):81-88, Tass, 2003. See also “Long-term anti-kindling effects of desynchronizing brain stimulation: a theoretical study,” Biol. Cybern 94(1):58-66, Tass, P. A., Majtanik M., and “Unlearning tinnitus-related cerebral synchrony with acoustic coordinated reset stimulation: theoretical concept and modelling,” Biol. Cybern. 106(1):27-36, Tass and Popovych, 2012.
Using the systematic tonotopic organization of the peripheral and central auditory system in the auditory cortex in the temporal lobe, acoustic tones, typically four different frequencies centered around the characteristic frequency of the patient's tinnitus percept, are determined and delivered in non-simultaneous sequences several hours per day for several weeks (lass et al., 2012). The four tones are designed to activate different areas of the central auditory system in a coordinated manner.
Despite their relative sophistication, many known acoustic CR techniques neuromodulation techniques do not provide or deliver stimulation signals that have intensities appropriately or optimally matched to the individual hearing thresholds of hearing impaired patients. What is needed are ways to deliver audio signals to hearing impaired patients where the signals have intensities that are optimally matched to individual hearing thresholds.